One of the most common therapies used to treat breast cancer is chemotherapy. Chemotherapy attacks cancer cells but it also attacks other cells in the body, so most people who undergo chemo will experience some side effects. Most side effects subside fairly quickly after treatment ends, according to the American Cancer Society. Here are some of the most common side effects caused by chemotherapy: 1. Hair, Skin and Nails Because chemotherapy attacks fast-growing cells like cancer cells, patients often experience sudden changes to hair, skin and nails that are also made up of fast growing cells. Hair loss is a well-known side effect probably because it is so visible, but patients also struggle with sore and dry skin, brittle nails, and skin discoloration. Learn 8 facts about chemotherapy and its side effects here.